The smith was working hard on making a new tool. A passer-by looked at his work and remarked that it looked sharp and dangerous. The smith nodded: it needed to be very sharp to do its work. The visitor wondered why there was no cross-guard to prevent the user’s hand to slide onto the blade, and why the design made it easy to accidentally grip the blade instead of the grip. The smith explained that the tool was intended for people who said they knew how to use it well. “But what if they were overconfident, sold it to somebody else, or had a bad day? Surely some safety measures would be useful?” “No”, said the smith, “my customers did not ask for them. I could make them with a slight effort, but why bother?”